(1). Field of the Invention
The present invention relates to fluid delivery systems and in particular, to an isolated compensated fuel delivery system for use in an underwater vessel.
(2). Description of the Prior Art
Underwater vessels, such as torpedoes, typically burn a liquid fuel contained in a fuel tank on the vessel. The emptying of the fuel tank as the fuel burns causes a change in the buoyancy of the underwater vessel that adversely affects the operation and movement of the vessel. Furthermore, free liquid surfaces of the fuel in a partially empty fuel tank can affect the stability of the underwater vessel or torpedo.
Conventional fuel delivery systems have displaced the liquid fuel with sea water as the fuel is burned to compensate for the loss of weight and volume of the burned fuel. One problem with this system is the corrosion in the aluminum fuel tanks when exposed to sea water and OTTO fuel, a monopropellant or fuel commonly used in torpedoes which has its own oxidizer that does not need air to provide oxygen. To prevent the corrosion, the fuel tanks must be flushed immediately after use with fresh water. Flushing the fuel tanks is time consuming, tedious and often not feasible.
One type of system uses a single bladder to separate the sea water from the fuel remaining in the tank, such as the type provided by BOFORS of Sweden. One disadvantage of this system is that existing fuel tanks, such as those used in heavyweight and lightweight torpedoes, would require extensive modifications to install the single bladder.